Author: Prof. Nona Dronova, D.Sc. ORCID: 0009-0007-4867-9074 Archive ID: GY-SS-GE-VAS-001 Repository: Antique Porcelain Archive (Zenodo)

Abstract

This study presents a technological reconstruction of the dual-crackle glaze (tie xian and secondary fissures) found in authentic Ge yao ware of the Southern Song dynasty (1127–1279). Drawing on visual, structural, and micro-analytical examination of a large, monochrome Ge-type vase from a verified private collection, this article documents the physical characteristics, glaze behavior, firing marks, and crackle formation mechanisms. High-resolution and microphotographic evidence support the identification of an achromatic dual-crackle system and reveal insight into kiln atmosphere, glaze formulation, and ceramic body-glaze fit.

1. Introduction

Ge yao (哥窑) remains one of the most technically intriguing types of Song dynasty official ceramics. Noted for their soft grey-blue glaze and complex crackle networks, these wares challenge attribution and technological replication. This paper proposes a reconstruction of their glaze formation through direct analysis of an authentic Southern Song vase (Cat. No. GY-SS-GE-VAS-001).

2. Object Description

• Type: Large bottle-form vase with disk-shaped mouth

• Date: 13th century (Southern Song dynasty)

• Attribution: Ge yao kiln, Zhejiang region (Longquan–Nanxun)

• Height: 40 cm

• Material: Porcelain with semi-translucent greyish-blue glaze

• Weight: Heavy (unmeasured)

• Glaze: Fully covering, thick, dual-crackle pattern

• Support: Five-point spur marks on recessed base

3. Structural and Micro-Analytical Observations

3.1 Overall Glaze Characteristics

The glaze layer is thick (~1–1.5 mm), semi-translucent, and opalescent under light reflection. It shows consistent application across both interior and exterior surfaces, including the recessed base.

3.2 Crackle System: Visual Evidence

Figure 1. Close-up of the glaze surface showing achromatic dual crackle structure.

The image shows large, dark crack lines (tie xian) intersected by pale, nearly colorless secondary fissures. The absence of yellow or ochre hues confirms that the dual crackle is achromatic, supporting the natural formation hypothesis.

Figure 2. Mouth rim macro showing continuity of crackle into interior.

The crackle network continues evenly from the mouth’s exterior into the throat, confirming glaze thickness and surface tension uniformity.

3.3 Microstructure and Primary Crackle Detail

Figure 3. Microphotograph of a primary “iron thread” crack showing pigment accumulation.

Under magnification, the tie xian fissure displays deep pigment deposition via capillary action. Microbubble dispersion within the glaze supports a calcium-silicate glaze composition fired under reduction.

3.4 Kiln Support and Base Examination

Figure 4. Lower wall and base junction showing five spur positions and dense basal crackle.

Figure 5. Top view of recessed base with visible spur scars and fine reticulated crackle.

The five-point spur mark layout, with vitrified iron halos, confirms authentic kiln stacking techniques. The unglazed footrim with blackened iron oxidation is typical for dragon kiln (longyao) firing.

3.5 Spur Mark Microstructure

Figure 6. Microphotograph of a spur mark with iron-rich residue and glaze recrystallization.

The transition zone between the vitrified spur residue and surrounding glaze shows high-temperature chemical fluxing and surface stress.

4. Glaze Formation and Reconstruction Protocol

Based on comparative observation and microanalytical imaging, the following sequence is proposed for Ge yao glaze formation:

This process explains the dual but achromatic crackle system without relying on artificial staining techniques.

5. Comparative Analysis

Museum parallels include:

• Palace Museum Beijing: Cat. No. 54, Ge yao vase with black crackle

• NPM Taipei: Inv. No. 故瓷01175, full-glazed base, dense spur evidence

• Percival David Foundation: PDF A69, spur marks and heavy crackle

All show similar base treatment, glaze pooling, and dual crackle features.

6. Conclusion

This case study confirms the authenticity and technological complexity of Ge yao glaze production. The documented vase demonstrates:

• Thick semi-translucent calcium-based glaze

• Naturally formed dual crackle: black tie xian + pale micro-fissures

• Firing in reducing conditions with five-point spur stacking

• Vitrified iron traces in spur marks and base oxidation

The findings support a historically plausible reconstruction of Ge yao firing and glaze development without resorting to modern staining methods. The vase is archived as an international reference sample under code GY-SS-GE-VAS-001.

References

1. Li Yuan, Gao Xiaoran, Dong Jianli et al. 《故宫博物院藏宋代官窑器釉的颜色无损测定》. Palace Museum Journal, 2023, pp. 405–413.

2. Dronova N.D. What You Need to Know About Ancient Chinese Porcelain. Moscow, 2017, p. 143.

3. Li Yiyang. Song Dynasty Official Kilns and Glaze Technology. Beijing: Cultural Relics Press, 2015.